He was, said Jeremy Hunt, a man of "integrity and decency" and his departure was a matter of "huge" personal regret. The Conservative culture secretary nonetheless swiftly accepted the resignation of his special adviser Adam Smith on Wednesday, prompting the Labour benches to accuse him of using his aide as a "human shield" who was "thrown to the wolves" to deflect attention away from his own close relationship with Rupert Murdoch's News Corp.

Smith announced his decision to quit after conceding on Wednesday morning that his "activities at times went too far".

The young policy adviser, described by one of his contacts in the sporting world as "Jeremy Hunt's mini-me", fell on his sword after correspondence between himself and the News Corporation lobbyist Frédéric Michel was aired at the Leveson inquiry.

His departure appeared to undermine the government's defence of Hunt. This centres on the charge that Michel had exaggerated, even outright distorted, accounts of his contact with Hunt and his team.

After Hunt gave a statement to the Commons, the Tory MP Mark Reckless said: "Do you agree that what these emails show is the shocking extent to which lobbyists exaggerate, embellish and invent the actual degree of access and influence they have?" Reckless was "exactly right", said Hunt.

But the Labour frontbencher Michael Dugher said the government was trying to paint Hunt's key policy adviser as a "Lee Harvey Oswald lone gunman", adding: "They've thrown the little guy to the wolves in order to save his boss's job."

The Labour MP Dennis Skinner asked Hunt: "Now your adviser has lost his job, doesn't it prove the theory that when posh boys are in trouble, they sack the servants?"

Intense attention will now focus on the precise role taken by the special adviser – or "spad" – in the BSkyB process, and the extent to which Hunt was aware of, or sanctioned, Smith's activities. Special advisers are a key part of any secretary of state's team: political appointees who are employed as civil servants but are free from the civil service requirement to show impartiality and objectivity.

One senior figure in the sporting world who met Smith regularly during his time working with Hunt, in government and opposition, said: "Adam's taken the bullet for Jeremy. Everyone knows spads are proxies for their bosses. Whenever I spoke to Adam, I knew that I was getting Jeremy. It was like talking to Jeremy." The pair even looked alike: "Adam was like Jeremy's mini-me."

Smith admitted he had told Michel more than he should have: "While it was part of my role to keep News Corporation informed throughout the BSkyB bid process, the content and extent of my contact was done without authorisation from the secretary of state.

"I do not recognise all of what Fréd Michel said, but nonetheless I appreciate that my activities at times went too far and have, taken together, created the perception that News Corporation had too close a relationship with the department, contrary to the clear requirements set out by Jeremy Hunt and the permanent secretary that this needed to be a fair and scrupulous process.

"Whilst I firmly believe that the process was in fact conducted scrupulously fairly, as a result of my activities it is only right for me to step down as special adviser to Jeremy Hunt."

An analysis of text messages and emails exchanged between Michel and Smith – and those sent from Michel to James Murdoch and other News Corp top brass relaying Smith's remarks – show Michel was largely passing on an accurate summary of the intelligence he was receiving from Hunt's camp.

As Michel himself admitted in his witness statement to Leveson, he frequently implied to Murdoch he had spoken to Hunt himself (JH), when in fact his contact was almost always Smith. But the fact remains the information Michel was relaying was usually a fair precis of what Smith told him by text or email, often just a few minutes previously.

On 2 February 2011, for example, Michel received a text from Smith informing him that the Office of Fair Trading was in charge of overseeing News Corp's bid for BSkyB. Smith wrote at 11.53am: "Oft leading but if they ask for ofcom help they will provide it." Less than half an hour later, Michel emailed Murdoch saying: "Just got news from JH. He confirmed that for him OFT was leading, but if they ask for Ofcom's help, they will provide it."

On 30 June 2011, Smith gave Michel a tip about that day's parliamentary questions, saying Labour MPs Tom Watson and Ivan Lewis had tabled urgent questions about the BSkyB bid. Smith then updates Michel with the times the questions will be asked – presumably so News Corp can tune into BBC Parliament.

Afterwards, Michel texted Smith to give his opinion on the parliamentary session, congratulating Hunt on a "solid performance!". He asks Smith whether a decision on the bid "can be made during recess". Smith replied within the hour, saying: "It can be made in recess. Jeremy keen to do it before if possible though." Ten minutes after receiving that text, Michel emailed Murdoch to say: "JH just told me that he was very keen to make the final decision before the 18th July. If needed his clearance CAN be made during recess but he is very keen to make it before that."

Those who know Michel say he was highly regarded within News Corp for his contacts across the political divide. A peerless networker, he was so plugged into all sides of the political establishment that he played tennis with the Liberal Democrat leader Nick Clegg and chose the Labour peer Lord Adonis as godfather to one of his three children.

In December 2010, 18 months after he started working for Murdoch, Michel was apparently approached to become the very highly paid spokesman for Lady Ashton, the much maligned "high representative" of the European Union. He didn't take the job.

He has been friends with Adonis since his time at the London School of Economics in the 1990s, and knows Clegg well – their children go to the same school in south London. Clegg's spokesman confirmed on Wednesday that the two used to be tennis partners until Clegg became deputy prime minister and had no time.

Michel was once close to the leading Labour party figure Peter Mandelson after both were involved in the founding of the centre-left thinktank Policy Network. However, the two fell out in 2003, causing Michel to leave the operation and move into lobbying for the reputation management firm ReputationInc. It was there, sanitising the images of important people, that he also got to know the Lib Dem foreign minister, Jeremy Browne, who worked at the firm until 2003.